1. Field:
This invention applies generally to the recovery of viscous bituminous material from natural formations containing same. In particular, the invention relates to a process for separating bitumen from tar sands. In addition the invention relates to recovering viscous oil deposits from oil wells and to secondary or tertiary recovery of petroleum from oil wells following primary oil recovery. In other words, the invention is generally valuable for use on all petroleum formations where problems of high viscosity and/or surface adhesion exist.
2. State of the Art:
Large deposits of oil sands or tar sands are found in various parts of the world, in particular in Canada, the United States of America, Venezuela, Russia, and Malagasy. Various attempts have been made in the past to recover the bituminous organic material from tar sands and oil sands. Retorting and other thermal processes are uneconomical due to the large quantity of heat consumed without any effective and efficient recovery thereof.
Processes utilizing water and a hydrocarbon diluent, such as kerosene, have been disclosed. For example, see U.S. Pat. Nos. 2,453,060; 2,825,677; and 3,509,037. Unfortunately, such processes utilize large amounts of heat and water. In addition, these processes are expensive and can cause serious environmental problems due to polluted water and sand which are produced in copious amounts.
Solvent extraction of bituminous organic material from tar sands or oil sands has also been proposed. For example, see U.S. Pat. Nos. 1,514,113; 2,453,633; 2,596,793; 3,050,289; 3,079,326; 3,131,141; 3,392,105; 3,475,318; 3,503,868; 3,509,037; 4,029,568; 4,046,668; 4,046,669; 4,057,485; and 4,110,194. Unfortunately, low yields, high energy consumption, loss of solvents, and environmental problems including dirty spent sands containing both solvent and bituminous material has hindered the development of the solvent extraction processes.
Problems are also encountered with recovery of viscous oil deposits from oil wells and with secondary and tertiary recovery of oil following primary oil recovery. Water and steam injections into the oil field have been used with moderate success. However, it is desirable to develop a more effective method of recovering petroleum from formations where problems of high viscosity and/or surface adhesion exist.
3. Objectives:
A principal objective of the present invention is to provide an efficient process of recovering high yields of bituminous organic material from tar sands, oil sands and other petroleum formations. A particular objective is to provide an efficient solvent vapor extraction process which is economical and which is environmentally clean, i.e., can be operated without polluting the ambient air and water. Another objective of the invention is to develop a process which requires a minimum of energy consumption and achieves a particularly efficient recovery of organic solvent with an effective reuse of heat values. A further objective is to provide a process which uses only small amounts of water, if any. A still further objective is to provide a process which can be used to recover bituminous materials from deposits which have been mined as well as in-situ from deposits within the earth which are economically unsuitable for application of conventional mining techniques.